Authors: Anouk van der Straten; Wieke van Leeuwen; Damiaan Denys; Hein van Marle; Guido van Wingen · Research

How Does Stress Affect Brain Networks in Obsessive-Compulsive Disorder?

Study examines how psychological stress impacts brain connectivity in OCD patients compared to healthy controls.

Source: van der Straten, A., van Leeuwen, W., Denys, D., van Marle, H., & van Wingen, G. (2020). The effect of distress on the balance between goal-directed and habit networks in obsessive-compulsive disorder. Translational Psychiatry, 10(1), 73. https://doi.org/10.1038/s41398-020-0744-7

What you need to know

  • Psychological stress altered brain connectivity differently in OCD patients compared to healthy controls
  • Stress reduced connectivity between goal-directed and default mode brain networks in healthy controls, but not in OCD patients
  • The altered stress response in OCD patients was associated with more severe compulsive symptoms
  • Findings suggest stress may interfere with goal-directed control in OCD, rather than enhancing habit behaviors

Background on OCD and Stress

Obsessive-compulsive disorder (OCD) is a mental health condition characterized by intrusive, anxiety-provoking thoughts (obsessions) and repetitive behaviors or mental acts (compulsions) performed to reduce anxiety. There are two main theories about what causes OCD symptoms:

  1. The cognitive-behavioral theory proposes that compulsions are performed to reduce distress caused by obsessions.

  2. The habit theory suggests OCD results from an imbalance between goal-directed and habit-related brain networks, with an overreliance on habitual behaviors.

However, these theories don’t fully explain how stress impacts OCD symptoms. This study aimed to bridge these theories by examining how psychological stress affects brain connectivity in OCD patients compared to healthy individuals.

How the Study Worked

The researchers recruited 23 OCD patients and 23 healthy control participants matched for age, gender, and education level. Participants completed two study sessions - one with a stressful task and one with a neutral control task.

For the stress condition, participants underwent the socially evaluated cold-pressor test:

  • Immersing their hand in ice-cold water for 3 minutes
  • Being observed and videotaped during the task
  • Performing mental arithmetic while their hand was in the cold water

The control condition involved placing their hand in room-temperature water without observation or additional tasks.

To measure stress responses, the researchers collected:

  • Cortisol levels from saliva samples
  • Blood pressure and heart rate
  • Self-reported anxiety levels

Participants then underwent brain scans approximately 65 minutes after the stress or control task. The researchers used resting-state functional magnetic resonance imaging (fMRI) to examine connectivity between different brain regions.

Key Findings on Brain Connectivity

The study focused on connectivity of two key brain networks:

  1. The goal-directed network, centered on the caudate nucleus
  2. The habit network, centered on the posterior putamen

Key findings included:

  • In healthy controls, stress reduced connectivity between the caudate nucleus and the precuneus, a region involved in self-referential thinking.

  • OCD patients did not show this stress-induced reduction in connectivity.

  • The altered stress response in OCD patients was associated with more severe compulsive symptoms.

  • Stress did not significantly impact connectivity of the habit network in either group.

What This Means for Understanding OCD

These results provide new insights into how stress may impact brain functioning in OCD:

  1. Stress appears to normally reduce connectivity between goal-directed and self-referential brain regions. This may help people disengage from internal thoughts and focus on goal-directed behaviors when under stress.

  2. In OCD, this stress-induced change in connectivity is blunted. This suggests patients may get “stuck” in self-referential thinking during stress, interfering with goal-directed control.

  3. The findings do not support the idea that stress enhances habit-related brain connectivity in OCD.

  4. The altered stress response was linked to compulsive symptoms, but not obsessive thoughts. This implies stress may particularly impact the compulsive behaviors in OCD.

Implications for Treatment

While this study did not test treatments directly, the findings have potential implications for OCD therapy:

  • Cognitive-behavioral therapy, the current gold-standard treatment, focuses on managing distress related to obsessive thoughts. This aligns with the finding that stress impacts goal-directed brain networks in OCD.

  • Therapies may benefit from incorporating more attention training techniques. This could help patients shift focus away from internal thoughts and enhance goal-directed control during stressful situations.

  • The results support the continued use of exposure therapy, where patients confront feared situations. This may help normalize the stress response over time.

Limitations and Future Directions

Some limitations of this study include:

  • The delay between the stress task and brain scans means acute stress effects may have been missed.

  • Most patients were taking medication, which could impact brain connectivity.

  • Resting-state brain scans don’t provide information about the direction of connectivity between regions.

Future research directions could include:

  • Examining brain connectivity during active goal-directed and habitual tasks, rather than at rest.

  • Investigating how different types of stress (e.g. acute vs. chronic) impact brain networks in OCD.

  • Testing how various OCD treatments influence stress-related brain connectivity.

Conclusions

  • Psychological stress impacts brain connectivity differently in people with OCD compared to healthy individuals.
  • In OCD, stress appears to interfere with the normal reduction in connectivity between goal-directed and self-referential brain networks.
  • This altered stress response is associated with more severe compulsive symptoms.
  • The findings help connect cognitive-behavioral and habit theories of OCD, suggesting stress may prevent disengagement from internal thoughts and interfere with goal-directed control.
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